There has been quite a lot of work done on this area. You could try Von Heijne, G. (1986) "A new method for predicting signal sequence sites" Nucl. Acids. Res. 14:4683-4690 for a start. Craig Marshall bioc07 at otago.ac.nz Department of Biochemistry Fax +64 3 479 7866 University of Otago Phone +64 3 479 7871 PO Box 56 Dunedin New Zealand